JP2010188496A - Machine tool and machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure rigidity with respect to the rotational direction of a table against external forces acting on a workpiece and to prevent an oscillation phenomenon. <P>SOLUTION: A machine tool includes: an speed feedback gain automatic setting device 16 that updates the speed feedback gain automatically; a sensor 10 that measures the rotational speed of a motor 7 that rotates a table 5 that supports a workpiece 11; and a control device 17 that performs a feedback control of the motor 7 based on the rotational speed thereof so that the angle of the table 5 coincides with a target angle, based on the speed feedback gain. In the machine tool 1, the speed feedback gain is variable, and when a proper value is substituted for the speed feedback gain, rigidity with respect to the rotational direction of the table 5 is ensured against external forces acting on the workpiece 11, and oscillation phenomenon can be prevented. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a machine tool and a machining method, and more particularly to a machine tool and a machining method used when machining gears.

  A machine tool that forms a gear using a hob is known. In hobbing, a gear is formed on the entire circumference of the workpiece by rotating the workpiece in synchronization with the hob cutter. That is, both the drive devices for driving the hob cutter and the workpiece are made to follow the target value by feeding back the displacement and speed to the target value.

  FIG. 1 shows a known machine tool. The machine tool 101 includes a machine tool main body 102 and a machine tool control device 103. The machine tool main body 102 includes a table 105, a cutter 106, a motor 107, a worm gear 108, and an encoder 109.

  The table 105 is supported by the base so as to be rotatable about a rotation axis parallel to the vertical direction. The table 105 has a support surface that is perpendicular to the rotation axis thereof, and supports the workpiece 110 that contacts the support surface. The workpiece 110 is generally formed in a disc shape. The cutter 106 is a hob, and is rotated by being controlled by an NC device (not shown) to cut the edge of the workpiece 110 and form teeth on the edge of the workpiece 110 to form the workpiece 110 into a gear. The motor 107 includes a shaft that is rotatably supported, and rotates the shaft based on an operation amount output from the machine tool control device 103. The worm gear 108 transmits the rotational power of the shaft of the motor 107 to the table 105 to rotate the table 105. The encoder 109 measures the rotational speed of the shaft of the motor 107 and outputs the rotational speed to the machine tool control device 103.

  The machine tool control device 103 includes a target value calculation unit 114, an integrator 115, and a control device 117. The target value calculation unit 114 collects NC data for processing the workpiece 110 into a gear and the operation of the cutter 106, and calculates a target angle based on the NC data and the operation. The integrator 115 calculates the angle of the table 105 by integrating the rotational speed of the shaft of the motor 107 measured by the encoder 109.

  The control device 117 includes an angle difference calculation unit 121, an angle feedback gain multiplication unit 122, a rotation speed difference calculation unit 123, a speed feedback gain multiplication unit 124, a proportional control unit 125, an integration control unit 126, and an addition unit 127. .

  The angle difference calculation unit 121 calculates the angle difference by subtracting the angle of the table 105 calculated by the integrator 115 from the target angle calculated by the target value calculation unit 114. The angle feedback gain multiplication unit 122 multiplies the angle difference calculated by the angle difference calculation unit 121 by a constant angle feedback gain to calculate the rotation speed amount. The rotation speed difference calculation unit 123 calculates the rotation speed difference by subtracting the rotation speed of the shaft of the motor 107 measured by the encoder 109 from the rotation speed amount calculated by the angle feedback gain multiplication unit 122. The speed feedback gain multiplication unit 124 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 123 by a constant speed feedback gain. The proportional control unit 125 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 124 by a constant proportional feedback gain. The integral control unit 126 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 124, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the integral operation amount. Is calculated. The adding unit 127 calculates an operation amount by multiplying the proportional operation amount calculated by the proportional control unit 125 by the integral operation amount calculated by the integration control unit 126.

  First, the operator places the workpiece 110 on the table 105 and inputs NC data for processing the workpiece 110 into a gear into an NC device (not shown). The NC device outputs the NC data to the machine tool control device 103, and rotates the cutter 106 based on the NC data. The target value calculation unit 114 of the machine tool control device 103 calculates a target angle based on the NC data. The integrator 115 of the machine tool control device 103 calculates the angle of the table 105 based on the rotational speed of the shaft of the motor 107 measured by the encoder 109.

  The angle difference calculation unit 121 of the control device 117 calculates the angle difference by subtracting the angle of the table 105 calculated by the integrator 115 from the target angle calculated by the target value calculation unit 114. The angle feedback gain multiplication unit 122 multiplies the angle difference calculated by the angle difference calculation unit 121 by a constant angle feedback gain to calculate the rotation speed amount. The rotation speed difference calculation unit 123 calculates the rotation speed difference by subtracting the rotation speed of the shaft of the motor 107 measured by the encoder 109 from the rotation speed amount calculated by the angle feedback gain multiplication unit 122. The speed feedback gain multiplication unit 124 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 123 by a constant speed feedback gain. The proportional control unit 125 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 124 by a constant proportional feedback gain. The integral control unit 126 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 124, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the integral operation amount. Is calculated. The adding unit 127 calculates an operation amount by multiplying the proportional operation amount calculated by the proportional control unit 125 by the integral operation amount calculated by the integration control unit 126.

  The motor 107 rotates the shaft based on the operation amount calculated by the adding unit 127. The worm gear 108 transmits the rotational power of the shaft of the motor 107 to the table 105 to rotate the table 105. With such an operation, the machine tool 101 forms the workpiece 110 into a gear by the cutter 106 cutting the edge of the workpiece 110 and forming teeth on the edge of the workpiece 110 as shown in the NC data.

  FIG. 2 shows another known machine tool. The machine tool 131 includes a machine tool main body 132 and a machine tool control device 133. The machine tool main body 132 includes a table 135, a cutter 136, a direct drive motor (DD motor) 137, and a rotary encoder 138.

  The table 135 is supported by the base so as to be rotatable about a rotation axis parallel to the vertical direction. The table 135 has a support surface that is perpendicular to the rotation axis thereof, and supports the work 139 that contacts the support surface. The work 139 is formed in a generally disc shape. The cutter 136 is rotated by being controlled by an NC device (not shown) to cut the edge of the workpiece 139 and form teeth on the edge of the workpiece 139 to form the workpiece 139 into a gear. The DD motor 137 includes a DD motor rotor 141 and a DD motor stator 142. The DD motor rotor 141 is fixed to the table 135. The DD motor stator 142 is fixed to the base. The DD motor 137 rotates the table 135 based on the operation amount output from the machine tool control device 133. The rotary encoder 138 measures the angle of the table 135 and outputs the angle to the machine tool control device 133.

  The machine tool control device 133 includes a target value calculation unit 114, a differentiator 145, and a control device 117. The target value calculation unit 114 calculates a target angle based on the NC data in order to process the workpiece 139 into a gear. The differentiator 145 calculates the rotational speed of the table 135 by differentiating the angle of the table 135 measured by the rotary encoder 138.

  The control device 117 includes an angle difference calculation unit 121, an angle feedback gain multiplication unit 122, a rotation speed difference calculation unit 123, a speed feedback gain multiplication unit 124, a proportional control unit 125, an integration control unit 126, and an addition unit 127. .

  The angle difference calculation unit 121 calculates the angle difference by subtracting the angle of the table 135 measured by the rotary encoder 138 from the target angle calculated by the target value calculation unit 114. The angle feedback gain multiplication unit 122 multiplies the angle difference calculated by the angle difference calculation unit 121 by a constant angle feedback gain to calculate the rotation speed amount. The rotation speed difference calculation unit 123 calculates the rotation speed difference by subtracting the rotation speed of the table 135 calculated by the differentiator 145 from the rotation speed amount calculated by the angle feedback gain multiplication unit 122. The speed feedback gain multiplication unit 124 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 123 by a constant speed feedback gain. The proportional control unit 125 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 124 by a constant proportional feedback gain. The integral control unit 126 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 124, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the integral operation amount. Is calculated. The adding unit 127 calculates an operation amount by multiplying the proportional operation amount calculated by the proportional control unit 125 by the integral operation amount calculated by the integration control unit 126.

  The embodiment of the machining method according to the present invention is executed using a machine tool 131. First, the worker places the workpiece 139 on the table 135 and inputs NC data for processing the workpiece 139 into a gear into an NC device (not shown). The NC device outputs the NC data to the machine tool control device 133, and rotates the cutter 136 based on the NC data. The target value calculation unit 114 of the machine tool control device 133 calculates a target angle based on the NC data. The differentiator 145 of the machine tool control device 133 calculates the rotation speed of the table 135 based on the rotation angle of the table 135 measured by the rotary encoder 138.

  The angle difference calculation unit 121 of the control device 117 calculates the angle difference by subtracting the angle of the table 135 calculated by the differentiator 145 from the target angle calculated by the target value calculation unit 114. The angle feedback gain multiplication unit 122 multiplies the angle difference calculated by the angle difference calculation unit 121 by a constant angle feedback gain to calculate the rotation speed amount. The rotation speed difference calculation unit 123 calculates the rotation speed difference by subtracting the rotation speed of the table 135 calculated by the differentiator 145 from the rotation speed amount calculated by the angle feedback gain multiplication unit 122. The speed feedback gain multiplication unit 124 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 123 by a constant speed feedback gain. The proportional control unit 125 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 124 by a constant proportional feedback gain. The integral control unit 126 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 124, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the integral operation amount. Is calculated. The adding unit 127 calculates an operation amount by multiplying the proportional operation amount calculated by the proportional control unit 125 by the integral operation amount calculated by the integration control unit 126.

  The DD motor 137 rotates the table 135 based on the operation amount calculated by the adding unit 127. By such an operation, the machine tool 131 forms the workpiece 139 into a gear by the cutter 136 cutting the edge of the workpiece 139 and forming teeth on the edge of the workpiece 139 as shown in the NC data.

  Such machine tools can ensure the rigidity in the table rotation direction against an external force acting on the workpiece by adjusting the constant of the feedback control system, for example, by increasing the gain of the speed feedback. However, when the gain is set high, a vibration phenomenon caused by the control system occurs. For this reason, machine tools such as these set constants so that vibration phenomena caused by the control system do not occur when machining all target workpieces, and all control constants are fixed at the time of shipment. Yes. A machine tool is desired to ensure the rigidity in the rotational direction of the table against an external force acting on the workpiece and to prevent an oscillation phenomenon.

  Japanese Patent No. 2996943 discloses a gear machining apparatus that improves machining efficiency by accurately detecting the machining completion time of the gear to be machined and ending the machining. The gear machining apparatus includes a motor for driving a cutter gear and a gear to be machined, an encoder for detecting rotation of each of the motors, PLL control means for controlling the motors to rotate in synchronization with each other, a cutter The PLL control unit includes a shift unit that sequentially shifts the rotational phases of the two motors according to a processing amount of the gear to be processed by the gear, and a unit that detects vibration in the processing unit. It is a jitter amount detecting means for detecting a phase fluctuation state of an input pulse from the encoder with respect to a command reference pulse given to each of the motors.

  Japanese Patent Application Laid-Open No. 07-88746 discloses in-process abnormalities during cutting (for example, increased wear or damage to the cutting edge of the tool) by performing a simple modification to an existing machine with a simple device. A cutting abnormality detection and emergency return method is disclosed in a gear processing machine, which measures the damage of the tool and machine and prevents the defect of the workpiece. The cutting abnormality detection and emergency return method in the gear processing machine is a gear processing machine that performs cutting while rotating a tool and a gear material to be processed at a constant rotation ratio. And a magnetoelectric or photoelectric detector, and by measuring fluctuations in the rotational frequency of the tool drive shaft, it is compared with the rotational frequency during normal cutting to detect abnormalities in the cutting state.

Japanese Patent No. 2969643 JP 07-88746 A

  An object of the present invention is to provide a machine tool and a machining method that ensure the rigidity in the rotation direction of a table against an external force acting on a workpiece and prevent an oscillation phenomenon.

  In the following, means for solving the problems will be described using the reference numerals used in the modes and examples for carrying out the invention in parentheses. This symbol is added to clarify the correspondence between the description of the claims and the description of the modes and embodiments for carrying out the invention. Do not use to interpret the technical scope.

  Machine tools (1), (41), and (61) according to the present invention include speed feedback gain automatic setting devices (16) and (71) that automatically update the speed feedback gain, and workpieces (11), (49), and (70). The angles of the sensors (9), (10), (48), and (69) that measure the sensor values related to the rotation of the supporting tables (5), (45), and (65) and the tables (5), (45), and (65) are the target angles. To the motors (7), (47), and (67) that rotate the tables (5), (45), and (65) based on the speed feedback gain so as to match 17). Such machine tools (1), (41), and (61) have variable speed feedback gains, and when an appropriate value is substituted for the speed feedback gain, the workpieces (11), (49), and (70). It is possible to secure the rigidity in the rotational direction of the tables (5), (45), and (65) with respect to the external force acting on and to prevent the oscillation phenomenon.

  The speed feedback gain automatic setting device (16) includes a vibration measuring unit (28) that calculates the degree of vibration based on the sensor value, and a speed feedback gain calculating unit that calculates the speed feedback gain based on the degree of vibration. (29) is preferably provided.

  The speed feedback gain is preferably increased when the degree of vibration is greater than a predetermined threshold.

  The sensors (9) (10) (48) (69) preferably include rotary encoders (9) (48) for measuring the angles of the tables (5) (45). At this time, the sensor value indicates the angle of the tables (5) and (45).

  The machine tools (1) (41) (61) according to the present invention have a target value calculation unit (14) that calculates a target angle based on NC data for forming gears on the workpieces (11) (49) (70). ). That is, such machine tools (1), (41), and (61) are suitable for gear processing machines that create gears.

  The speed feedback gain automatic setting device (71) refers to a workpiece material type collection unit (72) that collects material types of the workpiece (70), and a table that associates a plurality of material types with a plurality of speed feedback gains. A speed feedback gain calculating unit (73) that calculates the speed feedback gain corresponding to the material type from among the speed feedback gains is further provided.

  The workpiece material type collection unit (72) extracts the material type from data for processing the workpiece (70).

  In the machining method according to the present invention, the step of automatically updating the speed feedback gain and the sensor value relating to the rotation of the tables (5) (45) (65) supporting the workpieces (11) (49) (70) are measured. Based on the step and the speed feedback gain of the tables (5), (45), and (65), the motors (7) and (7) that rotate the tables (5), (45), and (65). 47) and (67) are feedback-controlled based on the sensor value. In such a machining method, the speed feedback gain is variable, and when an appropriate value is assigned to the speed feedback gain, the table (with respect to the external force acting on the work (11) (49) (70) ( 5) The rigidity in the rotational direction of (45) and (65) can be ensured, and the oscillation phenomenon can be prevented.

  The processing method according to the present invention preferably further includes a step of calculating the degree of vibration based on the sensor value and a step of calculating the speed feedback gain based on the degree of vibration.

  The speed feedback gain is preferably increased when the degree of vibration is greater than a predetermined threshold.

  The sensors (9) (10) (48) (69) preferably include rotary encoders (9) (48) for measuring the angles of the tables (5) (45). At this time, the sensor value indicates the angle of the tables (5) and (45).

  The machining method according to the present invention further includes a step of calculating the target angle based on NC data for forming the workpieces (11), (49) and (70) on the gears. That is, such machine tools (1), (41), and (61) are suitable for gear processing machines that create gears.

  The machining method according to the present invention refers to a step of collecting the material type of the workpiece (70) and a table associating a plurality of material types with a plurality of speed feedback gains, and corresponds to the material type from among the plurality of speed feedback gains. And calculating the speed feedback gain.

  The processing method according to the present invention preferably further comprises a step of extracting the material type from the data for processing the workpiece (70).

  The machine tool and the machining method according to the present invention can ensure the rigidity in the rotation direction of the table against an external force acting on the workpiece and can prevent an oscillation phenomenon.

FIG. 1 is a block diagram showing a known machine tool. FIG. 2 is a block diagram showing another known machine tool. FIG. 3 is a block diagram showing an embodiment of a machine tool according to the present invention. FIG. 4 is a graph showing changes in rigidity (compliance) when the table rotates when feedback controlling the motor using various speed feedback gains. FIG. 5 is a block diagram showing another embodiment of the machine tool according to the present invention. FIG. 6 is a block diagram showing another embodiment of the machine tool according to the present invention.

  An embodiment of a machine tool according to the present invention will be described with reference to the drawings. The machine tool 1 includes a machine tool body 2 and a machine tool control device 3 as shown in FIG. The machine tool main body 2 includes a table 5, a cutter 6, a motor 7, a worm gear 8, a rotary encoder 9, and an encoder 10.

  The table 5 is supported by a base so as to be rotatable about a rotation axis parallel to the vertical direction. The table 5 has a support surface that is perpendicular to the rotation axis thereof, and supports the workpiece 11 that contacts the support surface. The workpiece 11 is generally formed in a disc shape. The cutter 6 is controlled and rotated by an NC device (not shown) to cut the edge of the work 11 and form teeth on the edge of the work 11 to form the work 11 into a gear. The motor 7 includes a shaft that is rotatably supported, and rotates the shaft based on an operation amount output from the machine tool control device 3. The worm gear 8 transmits the rotational power of the shaft of the motor 7 to the table 5 and rotates the table 5. The rotary encoder 9 measures the angle of the table 5 and outputs the angle to the machine tool control device 3. The encoder 10 measures the rotational speed of the shaft of the motor 7 and outputs the rotational speed to the machine tool control device 3.

  The machine tool control device 3 includes a target value calculation unit 14, an integrator 15, a speed feedback gain setting device 16, and a control device 17. The target value calculation unit 14 collects NC data for processing the workpiece 11 into a gear and the operation of the cutter 6, and calculates a target angle based on the NC data and the operation. The integrator 15 calculates the angle of the table 5 by integrating the rotational speed of the shaft of the motor 7 measured by the encoder 10.

  The speed feedback gain setting device 16 updates the speed feedback gain based on the angle of the table 5 measured by the rotary encoder 9. That is, the speed feedback gain setting device 16 includes a vibration measuring unit 28 and a speed feedback gain calculating unit 29. The vibration measuring unit 28 calculates the degree of vibration of the table 5 based on the angle of the table 5 measured by the rotary encoder 9. The speed feedback gain calculation unit 29 calculates a speed feedback gain based on the degree of vibration calculated by the vibration measurement unit 28.

  Specifically, the speed feedback gain calculation unit 29 includes a storage device that records a threshold value and a plurality of speed feedback gains. The speed feedback gain calculation unit 29 initially outputs the minimum speed feedback gain among the plurality of speed feedback gains. The speed feedback gain calculating unit 29 is larger by one step than the currently output speed feedback gain among the plurality of speed feedback gains when the degree of vibration calculated by the vibration measuring unit 28 exceeds the threshold. Output speed feedback gain. That is, the speed feedback gain setting device 16 outputs only one of the plurality of speed feedback gains, and the speed feedback gain output by the speed feedback gain setting device 16 has an upper limit value and a lower limit value. . The speed feedback gain calculation unit 29 further selects a speed feedback gain that is greater than the speed feedback gain that the plurality of speed feedback gains are currently output and the degree of vibration calculated by the vibration measurement unit 28 exceeds the threshold value. When not included, it is determined as abnormal and the machine tool body 2 is stopped.

  The control device 17 uses the target angle calculated by the target value calculation unit 14, the angle of the table 5 calculated by the integrator 15, the rotational speed of the shaft of the motor 7 measured by the encoder 10, and the speed feedback gain setting device 16. Based on the set speed feedback gain, the motor 7 is feedback-controlled so that the angle of the table 5 matches the target angle calculated by the target value calculation unit 14.

  That is, the control device 17 includes an angle difference calculation unit 21, an angle feedback gain multiplication unit 22, a rotation speed difference calculation unit 23, a speed feedback gain multiplication unit 24, a proportional control unit 25, an integration control unit 26, and an addition unit 27. ing.

  The angle difference calculation unit 21 calculates the angle difference by subtracting the angle of the table 5 calculated by the integrator 15 from the target angle calculated by the target value calculation unit 14. The angle feedback gain multiplication unit 22 calculates the rotation speed amount by multiplying the angle difference calculated by the angle difference calculation unit 21 by an angle feedback gain that is a constant. The rotation speed difference calculation unit 23 calculates the rotation speed difference by subtracting the rotation speed of the shaft of the motor 7 measured by the encoder 10 from the rotation speed amount calculated by the angle feedback gain multiplication unit 22. The speed feedback gain multiplication unit 24 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 23 by the speed feedback gain set by the speed feedback gain setting device 16. The proportional control unit 25 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 24 by a constant proportional feedback gain. The integration control unit 26 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 24, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the operation amount. Is calculated. The adding unit 27 calculates the operation amount by multiplying the proportional operation amount calculated by the proportional control unit 25 by the integral operation amount calculated by the integration control unit 26. The amount of operation matches the amount of operation output by the control device 17.

  The embodiment of the machining method according to the present invention is executed using the machine tool 1. First, the operator places the workpiece 11 on the table 5 and inputs NC data for processing the workpiece 11 into a gear into an NC device (not shown). The NC device outputs the NC data to the machine tool control device 3, and rotates the cutter 6 based on the NC data. The target value calculation unit 14 of the machine tool control device 3 collects the NC data and the operation of the cutter 6 and calculates a target angle based on the NC data and the operation. The integrator 15 of the machine tool control device 3 calculates the angle of the table 5 based on the rotational speed of the shaft of the motor 7 measured by the encoder 10.

  The vibration measuring unit 28 of the speed feedback gain setting device 16 calculates the degree of vibration of the table 5 based on the angle of the table 5 measured by the rotary encoder 9. The speed feedback gain calculation unit 29 initially outputs the minimum speed feedback gain among a plurality of speed feedback gains recorded in advance in the storage device. The speed feedback gain calculating unit 29 is larger by one step than the currently output speed feedback gain among the plurality of speed feedback gains when the degree of vibration calculated by the vibration measuring unit 28 exceeds the threshold. Output speed feedback gain.

  The angle difference calculation unit 21 of the control device 17 calculates the angle difference by subtracting the angle of the table 5 calculated by the integrator 15 from the target angle calculated by the target value calculation unit 14. The angle feedback gain multiplication unit 22 calculates the rotation speed amount by multiplying the angle difference calculated by the angle difference calculation unit 21 by an angle feedback gain that is a constant. The rotation speed difference calculation unit 23 calculates the rotation speed difference by subtracting the rotation speed of the shaft of the motor 7 measured by the encoder 10 from the rotation speed amount calculated by the angle feedback gain multiplication unit 22. The speed feedback gain multiplication unit 24 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 23 by the speed feedback gain set by the speed feedback gain setting device 16. The proportional control unit 25 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 24 by a constant proportional feedback gain. The integration control unit 26 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 24, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the operation amount. Is calculated. The adding unit 27 calculates the operation amount by multiplying the proportional operation amount calculated by the proportional control unit 25 by the integral operation amount calculated by the integration control unit 26.

  The motor 7 rotates the shaft based on the operation amount calculated by the adding unit 27. The worm gear 8 transmits the rotational power of the shaft of the motor 7 to the table 5 and rotates the table 5. With this operation, the machine tool 1 forms the workpiece 11 into a gear by the cutter 6 cutting the edge of the workpiece 11 and forming teeth on the edge of the workpiece 11 as shown in the NC data.

  Furthermore, the speed feedback gain calculation unit 29 has a speed feedback gain that is greater than the speed feedback gain that the plurality of speed feedback gains are currently output, and the degree of vibration calculated by the vibration measurement unit 28 exceeds the threshold value. When not included, it is determined as abnormal, and the rotation of the cutter 6 and the rotation of the table 5 are stopped. According to such a stop, the machine tool control device 3 can prevent the table drive system from causing an oscillation phenomenon and becoming uncontrollable.

  FIG. 4 shows changes in rigidity (compliance) when the table 5 rotates when the motor 7 is feedback-controlled using a plurality of speed feedback gains. The change 31 indicates the rigidity related to the rotation of the table 5 when the motor 7 is feedback-controlled using a speed feedback gain indicating a certain value. The change 32 indicates the rigidity related to the rotation of the table 5 when the motor 7 is feedback-controlled using a speed feedback gain larger than the speed feedback gain when the rigidity of the change 31 is indicated. The change 33 indicates the rigidity related to the rotation of the table 5 when the motor 7 is feedback-controlled using a speed feedback gain larger than the speed feedback gain when the rigidity of the change 32 is indicated. The change 34 indicates the rigidity related to the rotation of the table 5 when the motor 7 is feedback-controlled using a speed feedback gain larger than the speed feedback gain when the rigidity of the change 33 is indicated. The change 35 indicates the rigidity related to the rotation of the table 5 when the motor 7 is feedback-controlled using a speed feedback gain larger than the speed feedback gain when the rigidity of the change 34 is indicated.

  Changes 31 to 35 indicate that the velocity feedback gain used for feedback control changes with respect to the frequency of the disturbance when the value is a certain value. Changes 31 to 35 further indicate that the rigidity when the table 5 rotates when the speed feedback gain is increased, and indicates that the rotation of the table 5 is less affected by disturbance. .

  That is, the machine tool 1 can automatically adjust the control constant (speed feedback gain) until the vibration of the workpiece 11 generated during gear machining falls within the threshold by executing such an operation. For this reason, the machine tool 1 can ensure the rigidity of the rotation direction of the table 5 with respect to the external force acting on the workpiece 11, and can prevent an oscillation phenomenon caused by the control system.

  The vibration measurement unit 28 can be replaced with another vibration measurement unit that calculates the degree of vibration of the table 5 based on the angle of the table 5 calculated by the integrator 15. Such a machine tool can ensure the rigidity in the rotation direction of the table 5 with respect to the external force acting on the workpiece 11 as well as the machine tool 1 in the above-described embodiment, and is caused by the control system. Oscillation phenomenon can be prevented. Such a machine tool can further omit the rotary encoder 9 and can be manufactured at a lower cost.

  The speed feedback gain calculation unit 29 may be replaced with another speed feedback gain calculation unit that calculates a speed feedback gain corresponding to the degree of vibration calculated by the vibration measurement unit 28. Such a machine tool can ensure the rigidity in the rotation direction of the table 5 with respect to the external force acting on the workpiece 11 as well as the machine tool 1 in the above-described embodiment, and is caused by the control system. Oscillation phenomenon can be prevented.

  FIG. 5 shows another embodiment of the machine tool according to the present invention. The machine tool 41 includes a machine tool main body 42 and a machine tool control device 43. The machine tool main body 42 includes a table 45, a cutter 46, a DD motor 47, and a rotary encoder 48.

  The table 45 is supported by the base so as to be rotatable about a rotation axis parallel to the vertical direction. The table 45 has a support surface that is perpendicular to the rotation axis thereof, and supports a work 49 that contacts the support surface. The work 49 is formed in a generally disc shape. The cutter 46 is formed of a hob-type grindstone, and is rotated by being controlled by an NC device (not shown) to cut the edge of the workpiece 49 and form teeth on the edge of the workpiece 49 to form the workpiece 49 into a gear. To do. The DD motor 47 includes a DD motor rotor 51 and a DD motor stator 52. The DD motor rotor 51 is fixed to the table 45. The DD motor stator 52 is fixed to the base. The DD motor 47 rotates the table 45 based on the operation amount output from the machine tool control device 43. The rotary encoder 48 measures the angle of the table 45 and outputs the angle to the machine tool control device 43.

  The machine tool control device 43 includes a target value calculation unit 14, a differentiator 55, a speed feedback gain setting device 16, and a control device 17. The target value calculation unit 14 collects NC data for processing the workpiece 49 into a gear and the operation of the cutter 46, and calculates a target angle based on the NC data and the operation. The differentiator 55 calculates the rotational speed of the table 45 by differentiating the angle of the table 45 measured by the rotary encoder 48.

  The speed feedback gain setting device 16 includes a vibration measuring unit 28 and a speed feedback gain calculating unit 29. The vibration measuring unit 28 calculates the degree of vibration of the table 45 based on the angle of the table 45 measured by the rotary encoder 48.

  The speed feedback gain calculation unit 29 includes a storage device that records a threshold value and a plurality of speed feedback gains. The speed feedback gain calculation unit 29 initially outputs the minimum speed feedback gain among the plurality of speed feedback gains. The speed feedback gain calculating unit 29 is larger by one step than the currently output speed feedback gain among the plurality of speed feedback gains when the degree of vibration calculated by the vibration measuring unit 28 exceeds the threshold. Output speed feedback gain. That is, the speed feedback gain setting device 16 outputs only one of the plurality of speed feedback gains, and the speed feedback gain output by the speed feedback gain setting device 16 has an upper limit value and a lower limit value. . The speed feedback gain calculation unit 29 further selects a speed feedback gain that is greater than the speed feedback gain that the plurality of speed feedback gains are currently output and the degree of vibration calculated by the vibration measurement unit 28 exceeds the threshold value. When not included, it is determined as abnormal and the machine tool main body 42 is stopped.

  The control device 17 includes an angle difference calculation unit 21, an angle feedback gain multiplication unit 22, a rotational speed difference calculation unit 23, a speed feedback gain multiplication unit 24, a proportional control unit 25, an integration control unit 26, and an addition unit 27. .

  The angle difference calculation unit 21 calculates the angle difference by subtracting the angle of the table 45 measured by the rotary encoder 48 from the target angle calculated by the target value calculation unit 14. The angle feedback gain multiplication unit 22 calculates the rotation speed amount by multiplying the angle difference calculated by the angle difference calculation unit 21 by an angle feedback gain that is a constant. The rotation speed difference calculation unit 23 calculates the rotation speed difference by subtracting the rotation speed of the table 45 calculated by the differentiator 55 from the rotation speed amount calculated by the angle feedback gain multiplication unit 22. The speed feedback gain multiplication unit 24 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 23 by the speed feedback gain set by the speed feedback gain setting device 16. The proportional control unit 25 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 24 by a constant proportional feedback gain. The integration control unit 26 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 24, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the operation amount. Is calculated. The adding unit 27 calculates the operation amount by multiplying the proportional operation amount calculated by the proportional control unit 25 by the integral operation amount calculated by the integration control unit 26.

  The embodiment of the machining method according to the present invention is executed using a machine tool 41. First, the operator places the workpiece 49 on the table 45, and inputs NC data for processing the workpiece 49 into a gear into an NC device (not shown). The NC device outputs the NC data to the machine tool control device 43, and rotates the cutter 46 based on the NC data. The target value calculation unit 14 of the machine tool control device 43 calculates a target angle based on the NC data. The differentiator 55 of the machine tool control device 43 calculates the rotation speed of the table 45 based on the rotation angle of the table 45 measured by the rotary encoder 48.

  The vibration measuring unit 28 of the speed feedback gain setting device 16 calculates the degree of vibration of the table 45 based on the angle of the table 45 measured by the rotary encoder 48. The speed feedback gain calculation unit 29 initially outputs the minimum speed feedback gain among a plurality of speed feedback gains recorded in advance in the storage device. The speed feedback gain calculating unit 29 is larger by one step than the currently output speed feedback gain among the plurality of speed feedback gains when the degree of vibration calculated by the vibration measuring unit 28 exceeds the threshold. Output speed feedback gain.

  The angle difference calculation unit 21 of the control device 17 calculates the angle difference by subtracting the angle of the table 45 calculated by the differentiator 55 from the target angle calculated by the target value calculation unit 14. The angle feedback gain multiplication unit 22 calculates the rotation speed amount by multiplying the angle difference calculated by the angle difference calculation unit 21 by an angle feedback gain that is a constant. The rotation speed difference calculation unit 23 calculates the rotation speed difference by subtracting the rotation speed of the table 45 calculated by the differentiator 55 from the rotation speed amount calculated by the angle feedback gain multiplication unit 22. The speed feedback gain multiplication unit 24 calculates a speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 23 by the speed feedback gain set by the speed feedback gain setting device 16. The proportional control unit 25 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 24 by a constant proportional feedback gain. The integration control unit 26 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 24, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the operation amount. Is calculated. The adding unit 27 calculates the operation amount by multiplying the proportional operation amount calculated by the proportional control unit 25 by the integral operation amount calculated by the integration control unit 26.

  The DD motor 47 rotates the table 45 based on the operation amount calculated by the adding unit 27. With this operation, the machine tool 41 forms the workpiece 49 into a gear by the cutter 46 cutting the edge of the workpiece 49 and forming teeth on the edge of the workpiece 49 as shown in the NC data.

  Furthermore, the speed feedback gain calculation unit 29 has a speed feedback gain that is greater than the speed feedback gain that the plurality of speed feedback gains are currently output, and the degree of vibration calculated by the vibration measurement unit 28 exceeds the threshold value. When not included, it is determined as abnormal, and the rotation of the cutter 46 and the rotation of the table 45 are stopped. According to such a stop, the machine tool control device 43 can prevent the table drive system from causing an oscillation phenomenon and becoming uncontrollable.

  That is, such a machine tool 41 performs such an operation, and in the same manner as the machine tool 1 in the above-described embodiment, provides the rigidity in the rotation direction of the table 45 with respect to the external force acting on the workpiece 49. The oscillation phenomenon caused by the control system can be prevented. That is, such a processing method can also be applied to control of the DD motor 47 that is directly connected to the table 45 and rotates the table 45.

  FIG. 6 shows still another embodiment of the machine tool according to the present invention. The machine tool 61 includes a machine tool main body 62 and a machine tool control device 63. The machine tool main body 62 includes a table 65, a cutter 66, a motor 67, a worm gear 68, and an encoder 69.

  The table 65 is supported by the base so as to be rotatable about a rotation axis parallel to the vertical direction. The table 65 has a support surface that is perpendicular to the rotation axis thereof, and supports the work 70 that contacts the support surface. The workpiece 70 is generally formed in a disc shape. The cutter 66 is controlled and rotated by an NC device (not shown) to cut the edge of the work 70, and by forming teeth on the edge of the work 70, the work 70 is formed into a gear. The motor 67 includes a shaft that is rotatably supported, and rotates the shaft based on an operation amount output from the machine tool control device 63. The worm gear 68 transmits the rotational power of the shaft of the motor 67 to the table 65 to rotate the table 65. The encoder 69 measures the rotational speed of the shaft of the motor 67 and outputs the rotational speed to the machine tool control device 63.

  The machine tool control device 63 includes a target value calculation unit 14, an integrator 15, a speed feedback gain setting device 71, and a control device 17. The target value calculation unit 14 collects NC data for processing the workpiece 70 into a gear and the operation of the cutter 66, and calculates a target angle based on the NC data and the operation. The integrator 15 calculates the angle of the table 65 by integrating the rotational speed of the shaft of the motor 67 measured by the encoder 69.

  The speed feedback gain setting device 71 calculates a speed feedback gain based on the NC data. That is, the speed feedback gain setting device 71 includes a workpiece material type collection unit 72 and a speed feedback gain calculation unit 73. The workpiece material type collecting unit 72 analyzes the NC data and extracts the material type of the workpiece 70 from the NC data.

  The speed feedback gain calculation unit 73 includes a storage device that records a table that associates a material type set and a speed feedback gain set. That is, that is, an arbitrary element in the material type set corresponds to one element in the velocity feedback gain set. Each element of the material type set indicates the material type of the material applied to the workpiece 70. Each element of the speed feedback gain set indicates the value of the speed feedback gain used in the control device 17. The speed feedback gain calculation unit 73 refers to the table and calculates a speed feedback gain corresponding to the material type extracted by the workpiece material type collection unit 72 from the speed feedback gain set.

  The control device 17 includes an angle difference calculation unit 21, an angle feedback gain multiplication unit 22, a rotational speed difference calculation unit 23, a speed feedback gain multiplication unit 24, a proportional control unit 25, an integration control unit 26, and an addition unit 27. .

  The angle difference calculation unit 21 calculates the angle difference by subtracting the angle of the table 65 calculated by the integrator 15 from the target angle calculated by the target value calculation unit 14. The angle feedback gain multiplication unit 22 calculates the rotation speed amount by multiplying the angle difference calculated by the angle difference calculation unit 21 by an angle feedback gain that is a constant. The rotation speed difference calculation unit 23 calculates the rotation speed difference by subtracting the rotation speed of the shaft of the motor 67 measured by the encoder 69 from the rotation speed amount calculated by the angle feedback gain multiplication unit 22. The speed feedback gain multiplication unit 24 multiplies the rotation speed difference calculated by the rotation speed difference calculation unit 23 by the speed feedback gain calculated by the speed feedback gain calculation unit 73 to calculate the speed operation amount. The proportional control unit 25 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 24 by a constant proportional feedback gain. The integration control unit 26 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 24, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the operation amount. Is calculated. The adding unit 27 calculates the operation amount by multiplying the proportional operation amount calculated by the proportional control unit 25 by the integral operation amount calculated by the integration control unit 26.

  The embodiment of the machining method according to the present invention is executed using a machine tool 61. The worker first places the workpiece 70 on the table 65 and inputs NC data for processing the workpiece 70 into a gear into an NC device (not shown). The NC device outputs the NC data to the machine tool control device 63, and rotates the cutter 66 based on the NC data. The target value calculation unit 14 of the machine tool control device 63 collects the NC data and the operation of the cutter 66, and calculates a target angle based on the NC data and the operation of the cutter 66. The integrator 15 of the machine tool control device 63 calculates the angle of the table 65 based on the rotational speed of the shaft of the motor 67 measured by the encoder 69.

  The workpiece material type collection unit 72 of the speed feedback gain setting device 71 calculates the material type of the material of the workpiece 70 based on the NC data. The speed feedback gain calculation unit 73 refers to a table associating the material type set with the speed feedback gain set, and the material extracted from the speed feedback gain set by the work material type collection unit 72 is referred to by the speed feedback gain calculation unit 73. The speed feedback gain corresponding to the seed is calculated.

  The angle difference calculation unit 21 of the control device 17 calculates the angle difference by subtracting the angle of the table 65 calculated by the integrator 15 from the target angle calculated by the target value calculation unit 14. The angle feedback gain multiplication unit 22 calculates the rotation speed amount by multiplying the angle difference calculated by the angle difference calculation unit 21 by an angle feedback gain that is a constant. The rotation speed difference calculation unit 23 calculates the rotation speed difference by subtracting the rotation speed of the shaft of the motor 67 measured by the encoder 69 from the rotation speed amount calculated by the angle feedback gain multiplication unit 22. The speed feedback gain multiplication unit 24 calculates the speed operation amount by multiplying the rotation speed difference calculated by the rotation speed difference calculation unit 23 by the speed feedback gain set by the speed feedback gain setting device 71. The proportional control unit 25 calculates a proportional operation amount by multiplying the speed operation amount calculated by the speed feedback gain multiplication unit 24 by a constant proportional feedback gain. The integration control unit 26 calculates an integral control amount by integrating the speed operation amount calculated by the speed feedback gain multiplication unit 24, and multiplies the integral control amount by an integral feedback gain that is a constant, thereby integrating the operation amount. Is calculated. The adding unit 27 calculates the operation amount by multiplying the proportional operation amount calculated by the proportional control unit 25 by the integral operation amount calculated by the integration control unit 26.

  The motor 67 rotates the shaft based on the operation amount calculated by the adding unit 27. The worm gear 68 transmits the rotational power of the shaft of the motor 67 to the table 65 to rotate the table 65. With this operation, the machine tool 61 forms the workpiece 70 as a gear by the cutter 66 cutting the edge of the workpiece 70 and forming teeth on the edge of the workpiece 70 as shown in the NC data.

  The rigidity in the rotation direction of the table 65 with respect to an external force acting on the workpiece 70 varies depending on the machinability and grindability of the workpiece 70. The machinability and grindability are specific to the material type of the material forming the workpiece 70. For this reason, the machine tool 61 can set the speed feedback gain more appropriately by appropriately creating the table recorded by the speed feedback gain calculator 73. When the speed feedback gain is appropriately set in this way, the machine tool 61 can ensure the rigidity in the rotational direction of the table 65 with respect to the external force acting on the workpiece 70, and oscillation caused by the control system The phenomenon can be prevented.

  The workpiece material type collecting unit 72 can be replaced with another workpiece material type collecting unit that collects the material type input from the input device via the input device included in the machine tool control device 63. In such a machine tool, the speed feedback gain can be set more appropriately in the same manner as the machine tool 61 in the above-described embodiment, and the rigidity in the rotation direction of the table 65 with respect to the external force acting on the workpiece 70 can be increased. The oscillation phenomenon caused by the control system can be prevented.

  The speed feedback gain setting device 71 initially calculates a speed feedback gain based on the material type of the workpiece 70, and thereafter, based on the vibration of the table 65, as in the above-described embodiment. A speed feedback gain can also be calculated. Also in the calculation of such speed feedback gain, the oscillation phenomenon can be prevented in the same manner as in the above-described embodiment.

DESCRIPTION OF SYMBOLS 1: Machine tool 2: Machine tool main body 3: Machine tool control apparatus 5: Table 6: Cutter 7: Motor 8: Worm gear 9: Rotary encoder 10: Encoder 11: Work piece 14: Target value calculation part 15: Integrator 16: Setting Device 17: Control device 21: Angle difference calculation unit 22: Angle feedback gain multiplication unit 23: Rotational speed difference calculation unit 24: Speed feedback gain multiplication unit 25: Proportional control unit 26: Integration control unit 27: Addition unit 28: Vibration measurement Unit 29: Speed feedback gain calculation unit 31 to 35: Change 41: Machine tool 42: Machine tool main body 43: Machine tool control device 45: Table 46: Cutter 47: DD motor 48: Rotary encoder 49: Work 51: DD motor rotor 52 : DD motor stator 55: Differentiator 61: Engineering Machine tool 62: Machine tool body 63: Machine tool control device 65: Table 66: Cutter 67: Motor 68: Worm gear 69: Encoder 70: Work piece 71: Setting device 72: Work material type collecting unit 73: Speed feedback gain calculating unit

Claims (14)

A speed feedback gain automatic setting device that automatically updates the speed feedback gain;
A sensor for measuring a sensor value related to rotation of the table supporting the workpiece;
A control device that feedback-controls a motor that rotates the table based on the sensor value based on the speed feedback gain so that the angle of the table matches a target angle. In claim 1,
The speed feedback gain automatic setting device is:
A vibration measuring unit that calculates the degree of vibration based on the sensor value;
A speed feedback gain calculating unit that calculates the speed feedback gain based on the degree of vibration. In claim 2,
The speed feedback gain increases when the degree of vibration is greater than a predetermined threshold. In any one of Claims 1-3,
The sensor includes a rotary encoder that measures an angle of the table,
The sensor value indicates an angle of the table. In any one of Claims 1-4,
A machine tool further comprising a target value calculation unit that calculates the target angle based on NC data for forming a gear on the workpiece. In claim 1,
The speed feedback gain automatic setting device is:
A workpiece material type collecting unit for collecting the material type of the workpiece;
A machine tool, further comprising: a speed feedback gain calculating unit that calculates the speed feedback gain corresponding to the material type from the plurality of speed feedback gains with reference to a table associating the plurality of material types and the plurality of speed feedback gains. In claim 6,
The workpiece material type collecting unit extracts the material type from data for processing the workpiece. Automatically updating the speed feedback gain;
Measuring a sensor value related to rotation of the table supporting the workpiece;
And a step of feedback-controlling a motor for rotating the table based on the sensor value based on the speed feedback gain so that the angle of the table matches a target angle. In claim 8,
Calculating the degree of vibration based on the sensor value;
And a step of calculating the speed feedback gain based on the degree of vibration. In claim 9,
The speed feedback gain increases when the degree of vibration is greater than a predetermined threshold. In any one of Claims 8-10,
The sensor includes a rotary encoder that measures an angle of the table;
The sensor value indicates an angle of the table. In any one of Claims 8-11,
A machining method further comprising: calculating the target angle based on NC data for forming a gear on the workpiece. In claim 8,
Collecting a grade of the workpiece;
And a step of calculating the speed feedback gain corresponding to the material type out of the plurality of speed feedback gains with reference to a table associating a plurality of material types with a plurality of speed feedback gains. In claim 13,
The processing method further comprising the step of extracting the material type from data for processing the workpiece.

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